Any OfficeSuite users? Confused on the difference between Pro app and Personal/Premium…

I’ve been looking for a good/cost effective app for opening and editing Microsoft office documents, including word/excel/PowerPoint. To me, OfficeSuite appears to be the best alternative to the Office365 membership. I’d rather pay $30/year for OfficeSuite than $99 for Office365. I’m only a little confused by their apps. I see an OfficeSuite Pro app for $20. This app appears to be a one time purchase. Then I see a free app with $30/year premium. Does anyone have experience with these apps and know which is the one to go with? $20 one time obviously sounds better i’m just honestly not sure the difference between the two. Thank you in advance!